Sir Roger Carr, the chairman of the United Kingdom’s largest defence contractor BAE Systems, said that he doesn’t believe the UK government would commission warships to be built in an independent Scotland.

Senior BAE trade union officials told Westminster’s Scottish Affairs Select Committee that staying in the UK is the only way to secure the future of shipbuilding in Scotland.

However, Yes Scotland campaigners say there is every reason to be confident that Scotland’s shipyards would have a healthy order book.

Glasgow north nest MP John Robertson, whose constituency takes in Scotstoun, has previously expressed concerns that the SNP’s plan to break up Britain will have a detrimental impact on Scotland’s defence sector.

Mr Robertson was unavailable for comment as he is currently in the USA on parliamentary business.

However, his concerns were echoed by his Labour colleague Iain McKenzie MP, who is Parliamentary Private Secretary to the Shadow Secretary of State for Defence, Vernon Coaker, who said: “It is now clearer than ever that, in the event of a ‘yes’ vote in September, hundreds of Inverclyde workers at BAE in Glasgow will pay the price.

“The Secretary of State for Defence, the Ministry of Defence, the Shadow Defence Secretary, BAE officials and union officials have been in total agreement over the future of Scotland’s shipyard sector.

“The UK builds warships for the United Kingdom. Should Scotland vote to leave the UK we would not, as a foreign country, receive contracts from the UK Government and the Ministry of Defence.” Sir Roger Carr was asked in a BBC interview about the prospect of a remaining UK Government placing shipbuilding orders in a separate Scotland, and replied: “We build warships in the United Kingdom for the United Kingdom,” and added there was no evidence that would change.

He also left open the possibility that BAE could resume shipbuilding at Portsmouth. Meanwhile, Henry Wilson, Unite staff convener at BAE, said trade unions were in ‘no doubt whatsoever’ that UK defence contracts would not be awarded to a foreign country, which is what Scotland would become.

Eric McLeod, GMB convener at BAE’s Rosyth yard, said it would be understandable that jobs could go to other UK shipyards if Scotland voted for separation.

However, Yes Scotland points out that Scottish shipyards already build ships for countries outside the UK. For example, BAE Systems sold three ships, including two built on the Clyde, to the Brazilian Navy.

It argues Scotland’s yards will “almost certainly” continue to receive orders from the UK’s Royal Navy and that Scotland does not get a good procurement deal from Westminster.

It highlights a parliamentary answer of October 3, 2011, estimated that out of the 6,000 small and medium sized enterprise contracts placed by the Ministry of Defence in 2010/11, only 50 contracts were in Scotland.

That is 0.83 per cent, despite the fact Scotland contributes around 9.5 per cent of the UK’s tax revenue and represent 8.4 per cent of the UK’s population.